1. Field of the Invention
The present invention pertains to laminated thermosetting foam board products and methods of making said products, utilizing a new and unique chemical agent to create a superior adhesion of the foam to a facer material.
2. Related Art and Other Considerations
Cellular organic plastic foams used for thermal insulation are well known in the art. Such foams can be made with urethane linkages, or made with a combination of both isocyanurate linkages and urethane linkages, or they can be made via the well known condensation reactions of formaldehyde with phenol, urea, and melamine. All such plastic foams must utilize an expansion agent, often referred to as a “blowing agent”. Much has been written regarding the improvement of insulation values via utilization of unique blowing agents, or combinations of blowing agents. Several other methods to improve insulation values include better surfactants and chemical additives.
If higher levels of water are used to expand foam, the surface interface of the foam to the facer can become friable, resulting in facer delamination. In the past, ethylene and propylene carbonates have been used to reduce the problematic surface friability. However, other problems were encountered using carbonates; e.g., they hydrolyze into their respective glycols. Free glycols use up large quantities of isocyanates, making poor foam.
Most of the rigid foam insulation manufactured goes into the building construction trade. To meet building codes and building insurance requirements, flame retardant materials are often added to these foams. These additives are usually organic halogens or phosphates, or combinations of organic halogens with phosphate included. Another means to improve flame resistance comprises the use of highly aromatic chemicals, since aliphatic organics are more prone to be flammable. Other additives can reduce friability and improve the facer adhesion.
The prior art is replete with references to techniques of rendering thermosetting foams more flame resistant, having better physical strength, and improving k-factors. In recent years, all of these method and products thereof have been taught in such United States patents as the following (all of which are incorporated herein by reference):
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Three (3) of the above listed patents teach the use of a common blend of industrial cleaning solvents called “Di-Basic Esters” (DBE) in thermosetting plastics. U.S. Pat. No. 5,102,919 teaches that the use of DBE significantly reduces the smoke generated by a flame retarded polyurethane/polyisocyanurate foam. U.S. Pat. No. 5,907,014 teaches that DBE reduces viscosity and improves “wettability” in an elastomeric polyurethane solid. Adhesion is not mentioned in either U.S. Pat. No. 5,102,919 or U.S. Patent No. 5,907,014.
Another use for DBE as a cell-opening agent in a low density polyurethane foam appears in U.S. Pat. No. 5,114,985. Without explanation, U.S. Pat. No. 5,114,985 states that foam adhesion can be reduced by silicone surfactants. The foam examples 1-5 teach that other variables (such as amounts of water and types of polyols) affect adhesion, but there is no recognition whether DBE has an effect on adhesion. Example number 3 stuck to the mold probably because it contained a lower level of water. Water is notorious for reducing adhesion by causing friability. Comparing examples 4 and 5 indicate that DBE in number 4 did not show better adhesion than number 5 without DBE. Furthermore, example 4 compared to examples 1 and 2 implies DBE has no effect on adhesion.
For many years, the dominant blowing agent used to expand thermosetting plastics into cellular foam for use as insulation was trichlorofluoromethane (CFC-11). This product had all the characteristics needed for foam insulation, but was determined to be a threat to stratospheric ozone. After trichlorofluoromethane (and all the “CFCs”) was phased out, the most common class of blowing agents became the hydrogenated chlorofluorocarbons (called “HCFCs”). These products are considered to be somewhat environmentally friendly expansion agents, but still contain some chlorine. However, the chlorine atoms of HCFCs are stable at altitudes under the stratosphere, so therefore they have a lower “Ozone Depleting Potential” (called “ODP”). But because they do have even a small ODP, the HCFCs have also been mandated for eventual phase out.
There is one chlorine containing molecule which the US EPA has approved for use as a blowing agent. This organic chloride is 2-chloropropane, CH3—CHCl—CH3. However, this substance is listed by the Environmental Defense Fund's (EDF's) Scorecard as a suspected health hazard. Two authoritative references on the subject are: Klaassen, C., M. Amdur and J. Doull (eds.). Casarett and Doull's Toxicology; and, The Basic Science of Poisons, 5th Ed. Pergamon Press, NY. 1996 (see Table 17-1: Cardiotoxicity of Key Pharmaceutical Agents, Table 17-2: Halogenated Hydrocarbons Reported to Have Arrhythimogenic Properties, Table 17-3: Cardiotoxicity of Selected Industrial Agents, Table 17-6: Vasculotoxic Agents: Heavy Metals, Table 17-7: Vasculotoxic Agents: Industrial and Environmental Agents, Table 17-8: Vasculotoxic Agents: Gases). This compound is listed as a suspected neurotoxicant and as a respiratory toxicant in the “National Institute for Occupational Safety and Health's (NIOSH's) Registry of Toxic Effects of Chemical Substances” (RTECS) (See EDF's Suspect Hazard Identification documentation).
Another known class of blowing agents is the non-chlorinated, partially hydrogenated fluorocarbons (called “HFCs”) which have the general formula: HxFyCz where x, y, and z are integers. The HFC compounds that have been approved for use as future expansion agents are HFC-134a, HFC-152a, and HFC-245fa. Some of these three compounds are now being utilized by either the aerosol industry or the refrigeration industry. This utilization factor has reduced the cost of these compounds whereby it may be affordable to use them as a portion, but not all, of the total blowing agent package. In view of the fact that about ten percent by weight of rigid foam insulation can be the compounds used as blowing agents, the still relatively high cost of HFCs needs to be offset by other, lower cost, expansion agents.
The US Environmental Protection Agency (“EPA”) refers to certain expansion agent compounds as “Saturated Light Hydrocarbons C3-C6”. These compounds are propane, isobutane, n-butane, isopentane, n-pentane, cyclopentane, and the various isomers of hexane. However, it has been discovered that when utilizing n-pentance as the sole expansion agent for a foam, the surface of the foam becomes too friable. This surface friability results in poor adhesion to the facer of a laminated foam board product. Poor adhesion of the facer to the foam of a laminated foam board insulation is intolerable.
What is needed, therefore, and an object of the present invention, is a low-cost insulation foam utilizing a suitable blowing agent and also having acceptable surface adhesion.